Mono-bore retrievable whipstock

ABSTRACT

A whipstock for mono-bore applications is disclosed which could be run in on wireline. The setting mechanism allows for a predetermined setting force to be applied to the anchor slip or slips before and automatic release from the running tool. The slips are further retained in position by a ratchet block, which is mounted to the whipstock body to work with the slips against release during removal of the milling equipment. The whipstock body is formed to place the upper end against the casing after the slips are driven out so that the onset of milling will not result in damage to the upper end. A retrieval tool engages an opening in the whipstock to release the grip of the slips and bring the assembly to the surface.

FIELD OF THE INVENTION

[0001] The field of this invention is whipstocks that can be set in cased holes and more particularly those that can be run in and set on wireline.

FIELD OF THE INVENTION

[0002] Whipstocks are used to guide milling systems to create a lateral in a wellbore both in cased wellbores with production tubing and those without production tubing. Applications for whipstocks without production tubing are called mono-bore and those applications with tubing are referred to as through tubing. Mono-bore applications have usually required the whipstock to land on a support such as a previously set anchor. Orientation tools would be used to detect the anchor receptacle orientation and the projection at the lower end of the whipstock would be set at the surface with respect to the whipstock tapered face so that upon engagement with the anchor receptacle, the whipstock face would have the proper orientation. Other designs involved a lower end actuation assembly for an anchoring system on the whipstock, which was actuated when the lower end struck a fixed object in the wellbore. One such design was made by Homco and referred to as the Bottomtrip Whipstock.

[0003] In mono-bore applications, whipstocks and anchors could be run together on rigid or coiled tubing and hydraulic pressure delivered through such tubing was used to set the anchor for support of the whipstock. In through tubing applications, such as illustrated in U.S. Pat. No. 5,909,770, a running tool which created relative movement could be run in on wireline to set slips on a through tubing whipstock, for creation of a lateral from below the production tubing. This patent revealed the use of the E-4 wireline setting tool to create the relative movement for a through tubing whipstock, which was subsequently retrievable.

[0004] In mono-bore applications, prior designs, because of the way the setting mechanisms were constructed, presented limitations on the applied setting force to land the slips against the casing. The act of setting such devices also tended to bring the upper end of the whipstock away from the casing wall where the milling system could readily engage and damage it. In the past, wireline was not considered a viable delivery system for whipstocks in mono-bore applications because the limited available stroke length for such a took was thought to be too short to apply the necessary setting force to anchor slips moved along an incline of about 7 degrees, which was an accepted industry optimum tradeoff value to ensure a sufficient gripping force with a limited amount of setting movement.

[0005] The apparatus and method of the present invention has, among other objectives, the goal of allowing fast run in times to depth in a mono-bore application while delivering a known high setting force to the anchor slips. The act of setting the whipstock also properly positions its upper end to avoid damage from milling. Another feature is resistance to release upon pullout of the milling system after drilling a lateral. The whipstock can be run into a mono-bore application on wireline or electric line and set with a Baker E-4 tool or the like with a predetermined applied force. These and other advantages of the present invention can be readily ascertained by one skilled in the art from a review of the description of the preferred embodiment, which appears below.

SUMMARY OF THE INVENTION

[0006] A whipstock for mono-bore applications is disclosed which could be run in on wireline. The setting mechanism allows for a predetermined setting force to be applied to the anchor slip or slips before and automatic release from the running tool. The slips are further retained in position by a ratchet block, which is mounted to the whipstock body to work with the slips against release during removal of the milling equipment. The whipstock body is formed to place the upper end against the casing after the slips are driven out so that the onset of milling will not result in damage to the upper end. A retrieval tool engages an opening in the whipstock to release the grip of the slips and bring the assembly to the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is an exploded view of the whipstock of the present invention:

[0008]FIG. 2 is a detailed view of the slip system in the run in position;

[0009]FIG. 3 is the view of FIG. 2 in the set position;

[0010]FIG. 4 is a section view through the slip system shown in the set position;

[0011]FIG. 5 is a perspective view of the upper end of the whipstock, which accepts the setting tool;

[0012]FIGS. 6a-6 c are a section view of the entire whipstock assembly in the run in position;

[0013]FIGS. 7a-7 c are the view of FIGS. 6a-6 c with the whipstock assembly in the set position;

[0014]FIGS. 8a-8 c are the view of FIGS. 7a-7 c with the whipstock assembly being retrieved.

[0015]FIG. 9 is a view of the whipstock body showing the fulcrum point, which allows the upper end to move toward the casing wall after setting the slip assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring to FIG. 1, the components of the whipstock assembly W comprise a whipstock body 10 having an upper end 12 and a lower end 14. A segment 16 is mounted at upper end 12 and shown in more detail in FIG. 5. FIG. 1 illustrates segment 16 from the back, while FIG. 5 illustrates the segment 16 rotated 180 degrees to illustrate the elongated recess 18, which co-acts with boss 20 on adapter sleeve 22. Boss 20 has a bore 24, which is aligned with trough 26 (see FIG. 5) on segment 16, when adapter sleeve 22 is assembled to segment 16. A tension rod 28 is connected to an adapter 32. Setscrews 30 lock it in place. The engagement of boss 20 to elongated recess 18 resists torque and provides a better guide to the whipstock assembly W during run in than the previous designs, which used a starter mill attached to a lug. It also provides a shoulder for boss 20 to transmit setting force through during setting of assembly.

[0017] Referring to FIG. 2, a slip body 34 is dovetail mounted to body 10 and slidably mounted to inclined surface 36 so that in the run in position of FIG. 2, no part of the slip body 34 or the hardened buttons 38 mounted to it extend out of body 10. Although one slip body is illustrated, multiple slip bodies can be employed without departing from the invention. The run in position of the slip body 34 is maintained by shear screws 40 inserted through openings 42 (see FIG. 1). Near the upper end 44 of inclined surface 36 there is a ratchet block 46 held down by a bar 48. There are wickers 50 on the top face of ratchet block 46 to engage the underside 52 of the slip body 34 (see FIG. 4). A bore 54 extends through body 10 to accommodate the tension rod 28.

[0018] Referring again to FIG. 1, the end of the tension rod 28 is inside shear ring 56. Shear ring 56 has an internal thread to match a thread at the end of tension rod 28. Initial upward movement of the tension rod 28 displaces a piston 58, which, in turn, displaces slip pins 60 into slip body 34. Such movement drives the slip body 34 up inclined surface 36 until the buttons 38 dig into the casing 62 (see FIG. 7c). After a predetermined force is applied with the buttons 38 contacting the casing 62, the tension rod threads 64 shear their mating threads in the shear ring 56 and the tension rod 28 along with adapter sleeve 22 and adapter 32 can come out of the hole (see FIGS. 7a-7 c). This type of shear release is rated for the full tensile rating of the rod. The position of the slip body 34 is held to casing 62 by the locking action of ratchet block 46. The preferred shear out force for the tension rod is at least 25,000 pounds but lesser values, which are still in excess of what can be reliably provided using shear pins into the tension rod 28, can be employed without departing from the invention. Accordingly values as low as 7,500 pounds would still provide an advantage over shear screws inserted into the tension rod 28. The use of the tension rod 28 which has no shear screws into it offers an advantage over prior setting systems in that a known large setting force can be counted upon as being applied to the slip body 34 when it is set.

[0019] Retrieval is shown in FIGS. 8a-8 c where an opening 68 is engaged with a hook shaped retrieving tool 70 to literally pull the ratchet block 46 out from under the slip body 34 so that body 10 can be retrieved from the wellbore.

[0020] Run in can be accomplished with a known wireline actuated setting tool which can cause a differential motion between the adapter sleeve 34, which receives a downward force, and the adapter 32 which transmits an opposed tensile force to tension rod 28. An E-4 wireline setting tool made by Baker Hughes can be used to do the setting. Alternatively coiled tubing combined with a pressure actuated setting tool can be used. The first thing that occurs when the E-4 tool is actuated is that shear pins 40 break and the tension rod 28 and all components connected to it move in tandem until the buttons 38 dig into the casing 62, at which point the slip body 34 becomes wedged. The applied force through tension rod 28 increases until the desired predetermined force is reached. At that point, the threads 64 shear out of the threads in the shear ring 66 and the E-4 setting tool and the tension rod are removed together. Those skilled in the art will appreciate that other wireline actuated setting tools can also be used to create the setting forces needed.

[0021]FIG. 9 illustrates another feature of the invention. The extension of the slip body 34 pivots the lower end 14 about the pivot point 66 preferably built into body 10 so as to get surface 68 near upper end 12 back as close as possible, if not in contact with the casing 62 despite the extension of the slip body 34 and its being locked in position by ratchet block 46. When milling begins, the top end 12 is less likely to be damaged, because it is out of harms way having been forced back against the casing 62. It should be noted that segment 16 is made of a soft material and is intended to be sacrificial, when milling a window begins.

[0022] The boss 20 extends into recess 18 of segment 16 to secure the alignment of adapter sleeve 22 to segment 16 as both receive a downward force from the setting tool (not shown) while at the same time the tension rod 28 receives a tensile force from the same setting tool.

[0023] A cap 68 on lower end 14 protects the tension rod 28 from damage during run in. Contact of objects in the wellbore by cap 68, will not result in accidental setting of the slip body. Once set, any uphole forces, such as when the mills are being extracted after milling the window will only tend to wedge the slip body 34 harder against the casing 62. Not only does the ramped surface 36 help to hold the set of slip block 34 but also the ratchet block 46 further secures the grip of slip body 34 when milling the window and when pulling the milling system out after the window is complete.

[0024] The use of a wireline setting tool to set the whipstock in a mono-bore application greatly reduces the time for the procedure. The configuration of the anchoring system with the slip body 34 moving on inclined surface 36 and then locked by ratchet block 46 in combination with the selected angle of surface 46 allows the use of wireline actuated setting tools in a mono-bore application for the first time. It should be noted that the preferred range of inclination for surface 36 is about 5-7 degrees. The ratchet block can be slidably mounted on a surface 70 which can be parallel or askew with regard to surface 36. Using a steeper or larger inclination angle on ratchet block 46 and mounting it for slidable movement while retained by bar 48 enhances the wedging action and hence the grip of the casing 62. The slope difference between surfaces 36 and 70 can be as large as about 4 degrees or even more.

[0025] The pivot point 66 acts to protect the upper end of body 10 by pushing it back against the casing 62.

[0026] The present invention can also be used in a through tubing application. References to wireline or electric line are intended to be interchangeable.

[0027] It is to be understood that this disclosure is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended other than as described in the appended claims. 

We claim:
 1. A method of making a lateral in a mono-bore, comprising: running in a whipstock and a setting tool on wireline; setting at least one slip to secure the whipstock in the mono-bore; producing the lateral.
 2. The method of claim 1, further comprising: ensuring a predetermined minimum force is applied to said slip after said slip is moved to a set position: thereafter releasing said setting tool from said whipstock.
 3. The method of claim 1, further comprising: moving said slip outwardly against said mono-bore to secure said whipstock; pivoting said whipstock about a pivot point, due to said moving of said slips outwardly to bring that portion of the upper end of the whipstock which is opposed to the sloping surface on the whipstock, closer to said mono-bore.
 4. The method of claim 2, further comprising: using a tension rod to move said slip to its said set position; using a ring at least in part surrounding said tension rod and, while selectively retained to said tension rod, allowing force to be transmitted to said slip in said set position.
 5. The method of claim 4, further comprising: using a mating thread between said tension rod and said ring, which pulls apart at the application of a predetermined force.
 6. The method of claim 5, wherein: said mating thread pulls apart with an applied force to said tension rod of at least about 7,500 pounds.
 7. The method of claim 1, further comprising: moving said slip on an inclined ramp to place it in a set position; locking said slip against movement back down said ramp after reaching its said set position.
 8. The method of claim 7, further comprising: accomplishing said locking with a locking member, which digs into said slip and is mounted on an incline at least as steep as said inclined ramp.
 9. A whisptock for downhole use, comprising: an elongated body having an external taper extending from near a top end thereof; at least one slip actuable outwardly toward a set position, in contact with a tubular downhole, by movement of an elongated member extending though said elongated body.
 10. The whipstock of claim 9, further comprising: a retainer at least in part circumscribing said elongated member and selectively releaseable there from after said slip has been moved to its said set position and an additional force of a predetermined value has been transmitted to said slip through said elongated member.
 11. The whipstock of claim 9, further comprising: an inclined ramp on said body on which said slip is operably movable by said elongated member, said slip movable outwardly from said body as it is urged along said ramp; a locking member to engage said slip after a predetermined movement along said ramp to selectively retain it against opposite movement along said ramp.
 12. The whipstock of claim 11, wherein: said locking member digs into said slip to selectively retain it and comprises a grip surface oriented on an angle at least as steep as said ramp.
 13. The whipstock of claim 9, wherein: said body comprises a pivot point such that extension of said slip pivots said body about said pivot point to bring the top end of said body, located opposite said external taper closer to the tubular downhole.
 14. The whipstock of claim 10, further comprising: an inclined ramp on said body on which said slip is operably movable by said elongated member, said slip movable outwardly from said body as it is urged along said ramp; a locking member to engage said slip after a predetermined movement along said ramp to selectively retain it against opposite movement along said ramp.
 15. The whipstock of claim 14, wherein: said locking member digs into said slip to selectively retain it and comprises a grip surface oriented on an angle at least as steep as said ramp.
 16. The whipstock of claim 15, wherein: said body comprises a pivot point such that extension of said slip pivots said body about said pivot point to bring the top end of said body, located opposite said external taper closer to the tubular downhole.
 17. The whipstock of claim 10, wherein: said predetermined force is at least about 7, 500 pounds.
 18. The whipstock of claim 9, further comprising: a setting tool operable on wireline and operably connected to said body and said elongated member to deliver the whipstock into a mono-bore and selectively apply a force to said elongated member to move said slip into its set position and to apply a predetermined force to said slip before forcing said elongated member to release for removal from said body with said setting tool.
 19. The whipstock of claim 18, further comprising: a retainer at least in part circumscribing said elongated member and selectively releasable therefrom after said slip has been moved to its said set position and an additional force of a predetermined value has been transmitted to said slip through said elongated member.
 20. The whipstock of claim 19, wherein: said body comprises a pivot point such that extension of said slip pivots said body about said pivot point to bring the top end of said body, located opposite said external taper closer to the tubular downhole.
 21. The method of claim 1, further comprising: providing a dovetail connection between said setting tool and said whipstock.
 22. The whipstock of claim 9, further comprising: a setting tool releasably connected to said body and rotationally locked thereto for selective actuation and retrieval of said elongated member.
 23. The whipstock of claim 12, wherein: said locking member is slidably mounted so as to increase holding force on said slip in response to an uphole force applied to said body.
 24. The whipstock of claim 10, wherein: said retainer releases at a value of shear up to the tensile capacity of said elongated member. 